1. Field of the Invention
The present invention relates to a serodiagnosis method for the detection of cancers, which comprises using an antigen recognizable by a human monoclonal antibody, particularly, the antigen derived from animals other than human.
2. The Prior Art
In these days, various reports have been published relating to a method for the preparation of human monoclonal antibodies which may react with cancer cells, which comprises culturing human-human hybridomas obtained by the fusion of antibody-producing cells from cancer patients with partner cells such as myeloma cells (Proc. Nat. Acad. Sci., U.S.A., 77, 6841 (1980); Brit. J. Cancer, 43, 105 and 696 (1981); Lancet, i 11 (1982); Eur. J. Cancer, 19, 347 (1983); J. Exp. Med., 159, 537 (1984); Cancer Res., 45, 263 and 3951 (1985); J. Immunol., 137, 1083 (1986)).
The human monoclonal antibodies described in these reports are not specific to cancer cells and may therefore react with normal cells as well. Furthermore, as antigens recognized by said monoclonal antibodies, substantially only ganglioside GM3 or GD3 which may be recognized by a human monoclonal antibody produced by a hybridoma has been known up to now (Proc. Nat. Acad. Sci., U.S.A., 84, 2416 (1987)). It thus appears that a serodiagnosis method for the detection of cancers, which comprises using an antigen recognizable by a human monoclonal antibody has not yet been disclosed till now. Similarly, there has been published up to now no serodiagnosis method for the detection of cancers, which comprises using an antigen recognizable by a human monoclonal antibody and derived from animals other than human.
Tumor markers conventionally used in an assay method for cancer such as a serodiagnosis one are derived from human. Such tumor markers may include embryonic proteins such as alpha-fetoprotein and carcinoembryonic antigen, blood group substances, hormones and isoenzymes. The assay method using such tumor markers can advantageously treat many samples in a simple manner and have been more important not only for screening cancers but also for monitoring therapeutic and postoperative effects.
However, the assay method using the above tumor markers or antigens conventionally known may not sufficiently detect cancers. In addition, it is very difficult to obtain the markers or antigens in a large amount, since they have their origin in human. Furthermore, since such antigens or markers may disadvantageously exist also in healthy individuals, their use would increase a ratio of false positives in the assay method. 0n the other hand, it is very difficult to diagnose cancers in their early stage by conventional assay methods which detect an amount of the tumor markers or antigens in blood because only a small amount thereof is present in that stage.